I have been with my boyfriend for over 2 years. I'm 18, so is he. We have tried to have sex, after a year together we tried and failed, he was o.k after it, we tried again after a month and he was upset after that one and then the third try failed again and he wouldn't try anymore for another year. When we have talked about it he always says that he really wants to, he gets nervous and that its never me. The last time, we had a plan to go away for a weekend to do it and although trying many times he would always get it up but never long enough to actually do anything. I have tried to help in loads of ways but nothing ever works. A few weeks ago, he broke up with me, because he "didn't feel the same way about me" a few days later he cry's on the phone wanting me back so I do. After a few weeks starting to trust him again, I want to have sex with him still. But we leave for university in 3 weeks and I don't know whether its me, him, if its worth being together through university or if we should call it quits before we go and get to know other people?
To clear up, my boyfriend is very sweet and says I'm gorgeous and he has never cheated on me, (although before we broke up he gave me a "free pass" which I was disgusted with) and I am his first girlfriend. We do have loads of fun together but lately I'm not sure if our fun is g/f & b/f or just as friends.

How old are you both?

It sounds like some part of him isn't ready for sex. At 18, it isn't that uncommon.

There can be several reasons ranging from fear of pregnancy to performance anxiety. Only he can tell you what his reasons are. Another common issue is pressure. If he feels pressured to have sex (it doesn't have to be logical), then his body may be responding negatively and shutting down. If that is the case, the more you (both of you) try to get him in the mood and ready, the worse it is going to be.

You can back off and give him more time or you can give up. It is going to have to be your choice since you would have a better idea of all the factors other than sex that are involved.

On the subject of your recent break up/make up, why did you take him back? Had the issues been resolved or are they still causing you doubts about the viability of the relationship?